The present invention relates generally to welding systems and, more particularly, to stick welder configured to deliver an arc creation output for a predefined period of time after an electrode strikes a workpiece and if an arc is not formed during that time period, then automatically deliver a low open circuit voltage (OCV) at a reduced current capability. The stick welder compares a sense voltage to a threshold and, based on that comparison, temporarily adjusts its output from a low OCV level to an arc creation level to provide a boosted output for arc creation between an electrode and a workpiece. After arc creation, the stick welder is designed to readjust its output to user-selected parameters, but if an arc is not timely formed, the stick welder lowers its output voltage from boosted level to the low OCV level at a lower current capability.
One common type of welding-type process is a stick or shielded metal arc welding (SMAW) process. During this process an electrode (stick/rod) comprising a wire core covered with a flux coating is used to deliver a welding arc. For a given SMAW process, it is desirable to control the power supply output to provide a desired voltage/amperage (V/A) curve. Typically, the desired power supply output V/A curve includes a substantially constant current portion within a typical operating voltage range and a “droop” portion where current decreases as voltage increases. Additionally, many welding-type devices provide a “dig” portion where the current increases as voltage decreases for a lower than normal operational voltage range.
To initiate an SMAW welding-type process, some welding-type devices rely upon a relatively low open circuit voltage (OCV) at a low current capability to facilitate arc creation between an electrode and a workpiece. With these devices, a relatively low OCV is maintained across the devices' output terminals until an arc is formed between an electrode and workpiece. Once an arc is formed, the welding-type device will adjust is output to match user-desired voltage and current levels. While it is desirable to have a relatively low OCV and current capability when not welding, the OCV and low current capability may be insufficient to initiate an arc between the electrode and workpiece. Accordingly, other SMAW systems are designed to provide a “boosted” output, called a hot start. In this regard, a boosted output voltage with a higher current capability is available to create an arc between an electrode and a workpiece. Generally, when a short circuit condition is detected between an electrode and workpiece, the SMAW system will adjust operation such that a voltage available for arc formation exceeds the low, stand-by OCV that is generally present before arc creation and that the higher OCV is available with greater current capability. The arc creation parameters are then maintained until an arc is formed between the electrode and workpiece, and a brief period thereafter. Notwithstanding the improved ease in arc formation, such known hot start systems do have drawbacks.
For example, the increased OCV with greater current capability will remain available until an arc is formed. This elevated voltage level is transmitted across a weld cable connecting the power source and the electrode of the SMAW system. The weld cable, however, can become damaged at a worksite and when carrying an elevated OCV, an unwanted arc can form between an exposed portion of the cable and an unexpectant ground.
It would therefore be desirable to have a stick welder capable of providing arc creation parameters for a short period of time to facilitate quick and repeatable arc formation between an electrode and a workpiece and if an arc is not timely formed, automatically adjust operation of the stick welder to a stand-by mode of operation where a relatively low OCV with a low current capability is applied to the output terminals of the stick welder.